The present invention relates to a technique for displaying picture information from an image apparatus connected to a display apparatus through an interface in the display apparatus.
In order to connect an image apparatus with an image display apparatus which is another image apparatus to make viewing and listening of picture, a method using analog connection to transmit picture and audio signals is used. However, with the spread of digital apparatuses, a method using digital connection to encrypt picture and audio signals to be transmitted is used from the viewpoint of prevention of deterioration in picture quality and protection of copyright.
The digital transmission using one cable conforming to the IEEE 1394 standard is known as an example thereof. In the digital transmission, mutual authentication is performed between a transmission apparatus and a receiving apparatus and picture and audio signals are multiplexed after the authentication, so that the multiplexed data is subjected to encryption processing named DTCP (Digital Transmission Content Protection) to be transmitted.
As another example, an HDMI (High-Definition Multimedia Interface) system is known. In the HDMI system, a baseband signal of a high definition picture signal and a audio signal are multiplexed in a time-shared manner and are subjected to encryption processing named HDCP (High-bandwidth Digital Content Protection) to be transmitted.
Such conventional technique in which the digitized picture and audio signals are multiplexed to be transmitted is disclosed in US 2003169370A1, for example.